Patent GB-763776-A (GB)
Title: Improvements in pre-registering and trimming machines for stereotype mats and plates
IPC: B41D1/00
Filed: 1955-01-19
Abstract: 763,776. Printing surfaces. BECH, J. Jan. 19, 1955, No. 1632/55. Class 100(2) A machine for pre-registering and trimming multi-colour stereotype mats and plates comprises a horizontally mounted drum upon which the mats or plates are secured by vacuum means and having oppositely disposed adjustable lamps for registering or control marks provided on the mats and plates, and electrically driven means mounted vertically above the drum for trimming the edges of the mats and plates. The mats are placed on the drum 5 (Fig. 1) which can be moved along a horizontal shaft 2 and locked in position. It can be rotated by means of a worm-drive operated by a hand wheel 4. A cutter head 8 is mounted to guide bar 7 supported by a pair of brackets 6 and is provided with an electric motor 10 for rotating the cutter shaft 9. The cutter head can be moved along the bar 7 by a chain 11 and a sprocket operated by the shaft 12 and hand wheel 13. The cutter is moved vertically by a treadle 14. The cutter wheel 30 is surmounted by a transparent shield 33. In operation the drum 5 is rotated by the wheel 4 so that a secondary vacuum plate 53, (Fig. 5), is fixedto the uppermost position. A valve 56 (Fig. 2) is then operated so that one of a plurality of mats con be fixed to the plate 53 by suction..The mats are provided with control marks at each corner. One of the control lamps, e.g. 23, is adjusted to register with one control mark and then moved along its slide bar 15 to register with the control mark at the other end of the mat. The mat is adjusted on the drum until the other control mark registers with the control lamp, thus ensuring alignment of the two marks parallel to the bar 15. The control lamps 22 and 23 are adjusted to register with the forward control marks and clamped in position. The two rear control lamps 26, 27 are similarly registered with the control marks on the other end of the mat and are also clamped in position. The trimming wheel 30 is then inserted in the cutter shaft 9, brought down by treadle 14, and the four edges of the mat trimmed. The mat is then removed. The next mat is similarly placed on the vacuum plate and adjusted so that the two foremost control marks register with the lamps 22, 23. The rear control marks should then register with the lamps 26, 27. If there is a deviation the mat is discarded. The mats are successively positioned and trimmed and stereotype plates are cast from them. To trim the plates the vacuum plate 53 and the trimming wheel 30 are removed. A milling cutter 34a, 34b (Fig. 4) is inserted into the cutter shaft 9. The drum is rotated through 180 degrees so as to bring the vaccum) plate uppermost (Fig. 5) and the first stereotype plate 39 is secured to plate 35. by operating the vacuum suction. Each stereotype plate has suction marks corresponding to those of the mats and is positioned and checked by the control lamps in the same way as the mats. Those which are warped and fail to register are discarded. When registered the face of the plate is grooved by the edge 34a of the milling cutter. The cutter shaft 9 is then further lowered so that the edge 34a trims the plate and the edge 34b trims a facet along the edge of the plate. Slight irregularities in the plates may be adjusted for by screws 57 attached to each end of the opposite edges of the vacuum plates 35. 53 so that these plates can be moved slightly in relation to each other. By this means' vacuum plates can be twisted slightly out of alignment to allow for the plates which are only slightly warped or shrunk. Plates which have a deviation of above a few tenths of a millimetre are discarded.